import numpy
import os
#from basinzoom import basinzoon
from ContourToMesh import ContourToMesh
import MatlabFuncs as m
import PythonFuncs as p

def FlagElements(md,region):
	"""
	FLAGELEMENTS - flag the elements in an region

	   The region can be given with an exp file, a list of elements or vertices

	   Usage: 
	      flag=FlagElements(md,region);

	   Example:
	      flag=FlagElements(md,'all');
	      flag=FlagElements(md,'');
	      flag=FlagElements(md,'Domain.exp');
	      flag=FlagElements(md,'~Domain.exp');
	"""

	if   isinstance(region,(str,unicode)):
		if   not region:
			flag=numpy.zeros(md.mesh.numberofelements,bool)
			invert=0
		elif m.strcmpi(region,'all'):
			flag=numpy.ones(md.mesh.numberofelements,bool)
			invert=0
		else:
			#make sure that we actually don't want the elements outside the domain outline!
			if m.strcmpi(region[0],'~'):
				region=region[1:]
				invert=1
			else:
				invert=0

			#does the region domain outline exist or do we have to look for xlim,ylim in basinzoom?
			if not os.path.exists(region):
				if len(region)>3 and not m.strcmp(region[-4:],'.exp'):
					raise IOError("Error: File 'region' not found!" % region)
				raise RuntimeError("FlagElements.py calling basinzoom.py is not complete.")
				xlim,ylim=basinzoom('basin',region)
				flag_nodes=p.logical_and_n(md.mesh.x<xlim[1],md.mesh.x>xlim[0],md.mesh.y<ylim[1],md.mesh.y>ylim[0])
				flag=numpy.prod(flag_nodes[md.mesh.elements],axis=1).astype(bool)
			else:
				#ok, flag elements
				[flag,dum]=ContourToMesh(md.mesh.elements[:,0:3].copy(),md.mesh.x,md.mesh.y,region,'element',1)
				flag=flag.astype(bool)

		if invert:
			flag=numpy.logical_not(flag)

	elif isinstance(region,numpy.ndarray) or isinstance(region,bool):
		if numpy.size(region,0)==md.mesh.numberofelements:
			flag=region
		elif numpy.size(region,0)==md.mesh.numberofvertices:
			flag=(numpy.sum(region[md.mesh.elements-1]>0,axis=1)==numpy.size(md.mesh.elements,1))
		else:
			raise TypeError("Flaglist for region must be of same size as number of elements in model.")

	else:
		raise TypeError("Invalid region option")

	return flag

